The cleansing of skin with surface-active cleansing preparations has become a focus of great interest. Many people wash and scrub their skin with various surface-active preparations several times a day. An ideal skin cleanser should cleanse the skin gently, causing little or no irritation, without defatting or overdrying the skin or leaving it taut after frequent routine use. Most lathering skin cleansers, liquids and bars, fail in this respect.
Synthetic detergent bars, frequently referred to as "syndet bars," are well known and are becoming increasingly popular. However, widespread replacement of soap bars by syndet bars has not so far been possible for a variety of reasons, primarily the different physical characteristics of syndet bars as compared to soap bars, e.g., processability, cost, smear or bar messiness, lather and rinse negatives.
The skin cleansing art is much more complex in our time. To improve skin cleansing mildness without processing and/or lather negatives, can be an unobvious and delicate balancing act.
It will be appreciated that rather stringent requirements for skin cleansers limit the choice of surface-active agents and final formulations represent some degree of compromise. Mildness is often obtained at the expense of effective cleansing and lathering. Conversely, mildness may be sacrificed for either preferred lathering characteristics, rinse feel, bar firmness, product stability, or all of the above. To provide an improvement or fix a problem in this art is usually more than mere optimization of the known art. There is an infinite number of ways to blend and tailor fatty acid soaps and synthetic surfactants. Which tailored soap blend is useful for a particular product or process is not always predictable.
A search of the bar soap literature will attest to the fact that those skilled in the art are still making improvements in the skin cleansing art.